1. Field of the Invention
The present invention relates to an expending plug designed particularly for use in combination with well packers, bridge plugs and the like, the plug resisting pressure surges from above and below the plug assembly.
2. Description of the Prior Art
Plug assemblies have been utilized and installed within the lower portion of the central bore of a well packer or other apparatus for location within a subterranena well at a predetermined depth. The packer, with the plug in place within its bore, may be utilized to isolate a plurality of production zones within the well for selective treatment of one or more of the zones.
When the first or upper zone has been treated and it is desired to either produce through the packer bore or treat the second or lower zone, a tubing string, either plain ended, or with an apparatus such as a mule shoe or the like inserted at its lower end, is inserted within the well and through the bore of the packer assembly to disengage the plug assembly from the well packer such that it is expended from the packer to the bore and free falls to the bottom of the well. If th plug is retrieved to the top of the well, the tubing or production string must be reinserted into the well and located immediate the well packer for production of the upper zone or for subsequent treatment or production of one or more zones therebelow.
Plug assemblies typical of the prior art are disclosed in the following U.S. patents: U.S. Pat. No. 3,002,563, entitled "Convertible Well Packer", issued Oct. 3, 1961, T. L. Crowe, Inventor; U.S. Pat. No. 3,131,765 entitled "Convertible Well Packer and Bridge Plug", issued May 5, 1964, W. D. Myers, Inventor; and U.S. Pat. No. 4,007,783, entitled "Well Plug With Anchor Means", issued Feb. 15, 1977, Amareswar Amancharla, et al, Inventors. Although each is an advancement in the art, these prior art assemblies, when compared to the present invention, are somewhat cumbersome, complex, expensive and timely to manufacture.
The present invention obviates the difficiencies found in the prior art by providing a plug assembly which may be expended from the bore of a well packer or other apparatus in a single trip such that the tubing utilized to expend the plug also may be utilized to produce or treat a second and lower zone without requirement of retrieval of the tubing subsequent to the plug expending operation.